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NASA NTRS1998

Rejoining and misrejoining of radiation-induced chromatin breaks. III. Hypertonic treatment

It has been shown that treatment in anisotonic medium modifies rejoining of radiation-induced breaks in interphase chromosomes. In previous work, we have demonstrated that formation of exchanges in human lymphocytes has a slow component (half-time of 1-2 h), but a fraction of exchanges are also observed in samples assayed soon after exposure. In this paper we studied the effect of hypertonic treatment on rejoining and misrejoining of radiation-induced breaks using fluorescence in situ hybridization of prematurely condensed chromosomes in human lymphocytes. Isolated lymphocytes were irradiated with 7 Gy gamma rays, fused to mitotic hamster cells and incubated in hypertonic solution (0.5 M NaCl) for the period normally allowed for interphase chromosome condensation to occur. The data from hypertonic treatment experiments indicate the presence of a class of interphase chromosome breaks that rejoin and misrejoin very quickly (half-time of 5-6 min). The fast misrejoining of these lesions is considered to be responsible for the initial level of exchanges which we reported previously. No significant effect of hypertonic treatment on the yield of chromosome aberrations scored at the first postirradiation mitosis was detected.

NASA Discipline Radiation Health↗

NASA NTRS2005

Two-Dimensional Ffowcs Williams/Hawkings Equation Solver

FWH2D is a Fortran 90 computer program that solves a two-dimensional (2D) version of the equation, derived by J. E. Ffowcs Williams and D. L. Hawkings, for sound generated by turbulent flow. FWH2D was developed especially for estimating noise generated by airflows around such approximately 2D airframe components as slats. The user provides input data on fluctuations of pressure, density, and velocity on some surface. These data are combined with information about the geometry of the surface to calculate histories of thickness and loading terms. These histories are fast-Fourier-transformed into the frequency domain. For each frequency of interest and each observer position specified by the user, kernel functions are integrated over the surface by use of the trapezoidal rule to calculate a pressure signal. The resulting frequency-domain signals are inverse-fast-Fourier-transformed back into the time domain. The output of the code consists of the time- and frequency-domain representations of the pressure signals at the observer positions. Because of its approximate nature, FWH2D overpredicts the noise from a finite-length (3D) component. The advantage of FWH2D is that it requires a fraction of the computation time of a 3D Ffowcs Williams/Hawkings solver.

Lockard, David P.↗

NASA NTRS2004

NASA Tech Briefs, October 2004

Topics include: Relative-Motion Sensors and Actuators for Two Optical Tables; Improved Position Sensor for Feedback Control of Levitation; Compact Tactile Sensors for Robot Fingers; Improved Ion-Channel Biosensors; Suspended-Patch Antenna With Inverted, EM-Coupled Feed; System Would Predictively Preempt Traffic Lights for Emergency Vehicles; Optical Position Encoders for High or Low Temperatures; Inter-Valence-Subband/Conduction-Band-Transport IR Detectors; Additional Drive Circuitry for Piezoelectric Screw Motors; Software for Use with Optoelectronic Measuring Tool; Coordinating Shared Activities; Software Reduces Radio-Interference Effects in Radar Data; Using Iron to Treat Chlorohydrocarbon-Contaminated Soil; Thermally Insulating, Kinematic Tensioned-Fiber Suspension; Back Actuators for Segmented Mirrors and Other Applications; Mechanism for Self-Reacted Friction Stir Welding; Lightweight Exoskeletons with Controllable Actuators; Miniature Robotic Submarine for Exploring Harsh Environments; Electron-Spin Filters Based on the Rashba Effect; Diffusion-Cooled Tantalum Hot-Electron Bolometer Mixers; Tunable Optical True-Time Delay Devices Would Exploit EIT; Fast Query-Optimized Kernel-Machine Classification; Indentured Parts List Maintenance and Part Assembly Capture Tool - IMPACT; An Architecture for Controlling Multiple Robots; Progress in Fabrication of Rocket Combustion Chambers by VPS; CHEM-Based Self-Deploying Spacecraft Radar Antennas; Scalable Multiprocessor for High-Speed Computing in Space; and Simple Systems for Detecting Spacecraft Meteoroid Punctures.

Source record↗

NASA NTRS2008

Fast Plasma Instrument for MMS: Data Compression Simulation Results

Magnetospheric Multiscale (MMS) mission will study small-scale reconnection structures and their rapid motions from closely spaced platforms using instruments capable of high angular, energy, and time resolution measurements. To meet these requirements, the Fast Plasma Instrument (FPI) consists of eight (8) identical half top-hat electron sensors and eights (8) identical ion sensors and an Instrument Data Processing Unit (IDPU). The sensors (electron or ion) are grouped into pairs whose 6 deg x 180 deg fields-of-view (FOV) are set 90 deg apart. Each sensor is equipped with electrostatic aperture steering to allow the sensor to scan a 45 deg x 180 deg fan about its nominal viewing (0 deg deflection) direction. Each pair of sensors, known as the Dual Electron Spectrometer (DES) and the Dual Ion Spectrometer (DIS), occupies a quadrant on the MMS spacecraft and the combination of the eight electron/ion sensors, employing aperture steering, image the full-sky every 30-ms (electrons) and 150-ms (ions), respectively. To probe the results in the DES complement of a given spacecraft generating 6.5-Mbs(exp -1) of electron data while the DIS generates 1.1-Mbs(exp -1) of ion data yielding an FPI total data rate of 6.6-MBs(exp -1). The FPI electron/ion data is collected by the IDPU then transmitted to the Central Data Instrument Processor (CIDP) on the spacecraft for science interest ranking. Only data sequences that contain the greatest amount of temporal/spatial structure will be intelligently down-linked by the spacecraft. Currently, the FPI data rate allocation to the CIDP is 1.5-Mbs(exp -1). Consequently, the FPI-IDPU must employ data/image compression to meet this CIDP telemetry allocation. Here, we present simulations of the CCSDS 122.0-B-1 algorithm-based compression of the FPI-DES electron data. Compression analysis is based upon a seed of re-processed Cluster/PEACE electron measurements. Topics to be discussed include: review of compression algorithm; data quality; data formatting/organization; and, implications for data/matrix pruning. To conclude a presentation of the base-lined FPI data compression approach is provided.

Barrie, A.↗

NASA NTRS1986

Rapid changes in H alpha-flares correlated with microwaves

The time evolution of several flares was studied in H alpha with a time resolution of 1.4 seconds. The time profiles of the linecenter intensity show fast fluctuations and spikes. During the impulsive phase, prominent spikes occur in different kernels and they are correlated with microwave and Hard X-ray spikes. Spectral resolved observations show major changes of the ratio between H alpha line width and H alpha linecenter intensity at time scales in the order of 1 minute. No significant fluctuations occurred at shorter time scales.

Wuelser, J-P.↗

NASA NTRS1975

Fast metastable fragments produced by dissociative excitation of carbonyl sulfide

Dissociative excitation of OCS by electron impact has been studied using the method of translational spectroscopy. Time-of-flight distributions and excitation functions of the fast metastable fragments have been measured. The results are compared with similar measurements on CO2 and show that a variety of metastable fragments including CO(a 3Pi), S(5S), O(5S) as well as long-lived high-lying atomic and molecular Rydberg fragments can contribute to dissociation.

Van Brunt, R. J.↗

NASA NTRS1994

Feasibility study, software design, layout and simulation of a two-dimensional Fast Fourier Transform machine for use in optical array interferometry

The goal of this project was the feasibility study of a particular architecture of a digital signal processing machine operating in real time which could do in a pipeline fashion the computation of the fast Fourier transform (FFT) of a time-domain sampled complex digital data stream. The particular architecture makes use of simple identical processors (called inner product processors) in a linear organization called a systolic array. Through computer simulation the new architecture to compute the FFT with systolic arrays was proved to be viable, and computed the FFT correctly and with the predicted particulars of operation. Integrated circuits to compute the operations expected of the vital node of the systolic architecture were proven feasible, and even with a 2 micron VLSI technology can execute the required operations in the required time. Actual construction of the integrated circuits was successful in one variant (fixed point) and unsuccessful in the other (floating point).

Boriakoff, Valentin↗

NASA NTRS2011

Fast Plasma Investigation for MMS: Simulation of the Burst Triggering System

The Magnetospheric Multiscale (MMS) mission will study small-scale reconnection structures and their rapid motions from closely spaced platforms using instruments capable of high angular, energy, and time resolution measurements. To meet these requirements, the Fast Plasma Instrument (FPI) consists of eight (8) identical half top-hat electron sensors and eight (8) identical ion sensors and an Instrument Data Processing Unit (IDPU). The sensors (electron or ion) are grouped into pairs whose 6 degree x 180 degree fields-of-view (FOV) are set 90 degrees apart. Each sensor is equipped with electrostatic aperture steering to allow the sensor to scan a 45 degree x 180 degree fan about the its nominal viewing (0 deflection) direction. Each pair of sensors, known as the Dual Electron Spectrometer (DES) and the Dual Ion Spectrometer (DIS), occupies a quadrant on the MMS spacecraft and the combination of the eight electron/ion sensors, employing aperture steering, image the full-sky every 30-ms (electrons) and 150-ms (ions), respectively. To probe the diffusion regions of reconnection, the highest temporal/spatial resolution mode of FPI results in the DES complement of a given spacecraft generating 6.5-Mb (raised dot) per second of electron data while the DIS generates 1.1-Mb (raised dot) per second of ion data yielding an FPI total data rate of 6.6-Mb (raised dot) per second. The FPI electron/ion data is collected by the IDPU then transmitted to the Central Data Instrument Processor (CIDP) on the spacecraft for science interest ranking. Only data sequences that contain the greatest amount of temporal/spatial structure will be intelligently down-linked by the spacecraft. This requires a data ranking process known as the burst trigger system. The burst trigger system uses pseudo physical quantities to approximate the local plasma environments. As each pseudo quantity will have a different value, a set of two scaling factors is employed for each pseudo term. These pseudo quantities are then combined at the instrument, spacecraft, and observatory level leading to a final ranking of data based on expected scientific interest. Here, we present simulations of the fixed point burst trigger system for the FPI. A variety of data sets based on previous mission data as well as analytical formulations are tested. Comparisons of floating point calculations versus the fixed point hardware simulation are shown. Analysis of the potential sources of error from overflows, quantization, etc. are examined and mitigation methods are presented. Finally a series of calibration curves are presented, showing the expected error in pseudo quantities based solely on the scale parameters chosen and the expected data range. We conclude with a presentation of the current base-lined FPI burst trigger approach.

Barrie, A. C.↗

NASA NTRS1993

The Pluto fast flyby mission: Completing the reconnaissance of the solar system

The concept of a fast flyby mission to Pluto has been advanced as a means to complete the reconnaissance of the known solar system. In order to acquire data on the Pluto system at the earliest possible time, and within the professional lifetime of investigators now active in the field, concepts are being developed for relatively small spacecraft in the mass range of 70 Kg to 350 Kg with flight times to Pluto of 7 to 13 years. Necessarily, the science complement on such a mission will be very mass and power limited. The challenge will be to define a spacecraft and an instrument package that will maximize the scientific return within these limitations. Cost, of course, will be a major consideration, and funds for new technology development specific to this mission will not be extensive. Consequently, innovative ways to incorporate elegant simplicity into the designs must be found. In order to facilitate exploration of the Pluto-Charon system, fully integrated science payloads must be developed. Two proposed mission designs involving limited mass and power science payloads have been presented to the Outer Planets Science Working Group (OPSWG). These payload mass allocations range from 5 to 30 kilograms with power allocations as low as 5 watts. The drivers behind these low mass and power allocations are that they enable developing missions to fit within the moderate mission cost profile and allow fast flight times to Pluto (7 to 13 years). The OPSWG has prioritized science goals for this class of reconnaissance mission. Three specific science objectives were identified as the highest priority required for the first Pluto mission. These goals were: (1) study of the neutral atmosphere, (2) geology and morphology, and (3) surface compositional mapping. In order to achieve these science goals within the constraints of low mass, power and cost, it may be necessary to combine the functions of 3 conventional instruments (CCD camera, Ultra-Violet Spectrometer, and Infrared Spectrometer) into one fully integrated payload. Where possible, this payload would share optics, mechanisms, electronics and packaging.

Henry, Paul K.↗

NASA NTRS1985

Interpretation of F-106B in-flight lightning signatures

Various characteristics of the electromagnetic data obtained on a NASA F-106B aircraft during direct lightning strikes are presented. Time scales of interest range from 10 ns to 400 microsecond. The following topics are discussed: (1) Lightning current, I, measured directly versus I obtained from computer integration of measured I-dot; (2) A method of compensation for the low frequency cutoff of the current transformer used to measure I; (3) Properties of fast pulses observed in the lightning time-derivative waveforms; (4) The characteristic D-dot signature of the F-106B aircraft; (5) An RC-discharge interpretation for some lightning waveforms; (6) A method for inferring the locations of lightning channel attachment points on the aircraft by using B-dot data; (7) Simple, approximate relationships between D-dot and I-dot and between B and I; and (8) Estimates of energy, charge, voltage, and resistance for a particular lightning event.

Trost, T. F.↗

NASA NTRS2007

ShareSync: A Solution for Deterministic Data Sharing over Ethernet

As part of upgrading the Contact Dynamics Simulation Laboratory (CDSL) at the NASA Marshall Space Flight Center (MSFC), a simple, cost effective method was needed to communicate data among the networked simulation machines and I/O controllers used to run the facility. To fill this need and similar applicable situations, a generic protocol was developed, called ShareSync. ShareSync is a lightweight, real-time, publish-subscribe Ethernet protocol for simple and deterministic data sharing across diverse machines and operating systems. ShareSync provides a simple Application Programming Interface (API) for simulation programmers to incorporate into their code. The protocol is compatible with virtually all Ethernet-capable machines, is flexible enough to support a variety of applications, is fast enough to provide soft real-time determinism, and is a low-cost resource for distributed simulation development, deployment, and maintenance. The first design cycle iteration of ShareSync has been completed, and the protocol has undergone several testing procedures including endurance and benchmarking tests and approaches the 2001ts data synchronization design goal for the CDSL.

Dunn, Daniel J., II↗

NASA NTRS2008

Stereoscopic Imaging in Hypersonics Boundary Layers using Planar Laser-Induced Fluorescence

Stereoscopic time-resolved visualization of three-dimensional structures in a hypersonic flow has been performed for the first time. Nitric Oxide (NO) was seeded into hypersonic boundary layer flows that were designed to transition from laminar to turbulent. A thick laser sheet illuminated and excited the NO, causing spatially-varying fluorescence. Two cameras in a stereoscopic configuration were used to image the fluorescence. The images were processed in a computer visualization environment to provide stereoscopic image pairs. Two methods were used to display these image pairs: a cross-eyed viewing method which can be viewed by naked eyes, and red/blue anaglyphs, which require viewing through red/blue glasses. The images visualized three-dimensional information that would be lost if conventional planar laser-induced fluorescence imaging had been used. Two model configurations were studied in NASA Langley Research Center's 31-Inch Mach 10 Air Wind tunnel. One model was a 10 degree half-angle wedge containing a small protuberance to force the flow to transition. The other model was a 1/3-scale, truncated Hyper-X forebody model with blowing through a series of holes to force the boundary layer flow to transition to turbulence. In the former case, low flowrates of pure NO seeded and marked the boundary layer fluid. In the latter, a trace concentration of NO was seeded into the injected N2 gas. The three-dimensional visualizations have an effective time resolution of about 500 ns, which is fast enough to freeze this hypersonic flow. The 512x512 resolution of the resulting images is much higher than high-speed laser-sheet scanning systems with similar time response, which typically measure 10-20 planes.

Danehy, Paul M.↗

NASA NTRS1993

Exploring the southern ocean response to climate change

The purpose of this project was to couple a regional (Southern Ocean) ocean/sea ice model to the existing Goddard Institute for Space Science (GISS) atmospheric general circulation model (GCM). This modification recognizes: the relative isolation of the Southern Ocean; the need to account, prognostically, for the significant air/sea/ice interaction through all involved components; and the advantage of translating the atmospheric lower boundary (typically the rapidly changing ocean surface) to a level that is consistent with the physical response times governing the system evolution (that is, to the base of the fast responding ocean surface layer). The deeper ocean beneath this layer varies on time scales several orders of magnitude slower than the atmosphere and surface ocean, and therefore the boundary between the upper and deep ocean represents a more reasonable fixed boundary condition.

Martinson, Douglas G.↗

NASA NTRS1985

NPLOT: an Interactive Plotting Program for NASTRAN Finite Element Models

The NPLOT (NASTRAN Plot) is an interactive computer graphics program for plotting undeformed and deformed NASTRAN finite element models. Developed at NASA's Goddard Space Flight Center, the program provides flexible element selection and grid point, ASET and SPC degree of freedom labelling. It is easy to use and provides a combination menu and command driven user interface. NPLOT also provides very fast hidden line and haloed line algorithms. The hidden line algorithm in NPLOT proved to be both very accurate and several times faster than other existing hidden line algorithms. A fast spatial bucket sort and horizon edge computation are used to achieve this high level of performance. The hidden line and the haloed line algorithms are the primary features that make NPLOT different from other plotting programs.

Jones, G. K.↗

NASA NTRS2010

IT Research Services: Powerful Tools to Track a Fast Moving Industry

Research services change and evolve over time, sometimes suddenly, in their focus, topics, formats, service model, etc. You have to check in often. Some offer products that you can customize to your environment, others not so much. You will find a variation in customer management practices (e.g., when and how they share information) ...can sometimes be annoying. Assess your needs carefully. Each research service has a very different service model. Explore ways to share or lower the cost. Someone out there may share the expense when that is an option. Make sure you read the small print. It can work for you as well as against you. When in doubt, ask your Vendor's POC. Set up Research Service "gurus or SME's." Not to violate the copyright agreement of course, just have someone who knows what's there. After you subscribe, reassess.Get the most out of your investment. Some early enthusiasts will fade, and there will be others who don't know it's there and can use it.

Hunter, Paul↗

NASA NTRS2010

Fast Multivariate Search on Large Aviation Datasets

Multivariate Time-Series (MTS) are ubiquitous, and are generated in areas as disparate as sensor recordings in aerospace systems, music and video streams, medical monitoring, and financial systems. Domain experts are often interested in searching for interesting multivariate patterns from these MTS databases which can contain up to several gigabytes of data. Surprisingly, research on MTS search is very limited. Most existing work only supports queries with the same length of data, or queries on a fixed set of variables. In this paper, we propose an efficient and flexible subsequence search framework for massive MTS databases, that, for the first time, enables querying on any subset of variables with arbitrary time delays between them. We propose two provably correct algorithms to solve this problem (1) an R-tree Based Search (RBS) which uses Minimum Bounding Rectangles (MBR) to organize the subsequences, and (2) a List Based Search (LBS) algorithm which uses sorted lists for indexing. We demonstrate the performance of these algorithms using two large MTS databases from the aviation domain, each containing several millions of observations Both these tests show that our algorithms have very high prune rates (>95%) thus needing actual

Bhaduri, Kanishka↗

NASA NTRS1992

A fast operator perturbation method for the solution of the special relativistic equation of radiative transfer in spherical symmetry

A fast method for the solution of the radiative transfer equation in rapidly moving spherical media, based on an approximate Lambda-operator iteration, is described. The method uses the short characteristic method and a tridiagonal approximate Lambda-operator to achieve fast convergence. The convergence properties and the CPU time requirements of the method are discussed for the test problem of a two-level atom with background continuum absorption and Thomson scattering. Details of the actual implementation for fast vector and parallel computers are given. The method is accurate and fast enough to be incorporated in radiation-hydrodynamic calculations.

Hauschildt, P. H.↗

NASA NTRS1994

Electron time dispersion

Observations of electrons during a sounding rocket flight from Sondrestromfjord, Greenland, in 1985 showed numerous instances of electron time-of-flight dispersion, that is, a coherent structure in which fast electrons arrived before slow electrons. The instrumentation measured many pitch angles simultaneously with high time resolution, providing a detailed view of the temporal evolution of the electron signature at rocket altitudes which was indicative of an impulsive injection of electrons over a range of energies. A model utilizing an extended, quasi-static (static on a timescale of 1 s), parallel electric field was developed to investigate a possible mechanism for the injection of these electrons. The model is found to fit the data well only when a background is added which cannot be self-consistently generated by the model, although other parameters used in the model are in general agreement with previous reports. This leads to the conclusion that electron dispersion is more probably generated by a wave acceleration mechanism.

Kletzing, C. A.↗